The present invention relates to a laser machining apparatus, and more particularly to a laser machining apparatus and its control method suitable for drilling holes in a circuit board formed by laminating an insulating layer and a conductive layer.
Generally, circuit boards include the type called multilayer circuit board formed by laminating an insulating layer and a conductive layer alternately, and such multilayer circuit board is effective for enhancing the mounting density, and has come to be used widely.
Specifically, in the multilayer circuit board, holes are drilled in the insulating layer, and the holes are filled with solder or conductive paste to achieve conduction between adjacent conductive layers.
As the processing technology for drilling holes in such insulating layer, laser machining is widely employed.
The wavelength of the laser beam to be used is selected at a wavelength easy to be absorbed in the insulating layer and easy to be reflected in the conductive layer. For example, if the insulating layer is a glass epoxy resin and the conductive layer is a copper foil, carbon dioxide laser beam is used, so that the insulating layer only can be removed selectively.
It is important to drill holes so as to achieve conduction securely between adjacent conductive layers.
A prior art is disclosed, for example, in Japanese Laid-open patent No. 2-92482. According to this publication, when drilling holes in the workpiece by irradiating laser beam, the direct outputted beam from the laser output unit and the reflected beam from the workpiece are detected by individual sensors, and the reflected beam quantity ratio is calculated from the both beam quantities, then the laser beam is controlled by comparison with the reference value.
More specifically, when the reflected beam quantity ratio becomes larger than a predetermined reference value, the output unit is stopped.
By such operation, damage of conductive layer by laser beam is prevented, and the processing time is shortened at the same time.
The prior art, however, had the following problems.
That is, in the conventional machining method, only the reflected beam from the workpiece was detected. If the surface of the conductive layer for reflecting the laser beam of the workpiece is contaminated to absorb the laser beam due to some cause, the level of the reflected beam may not reach the specified level. As a result, excessive machining or abnormal heating may occur. When machining the workpiece, therefore, holes may not be drilled to a desired shape. This is one of the problems of the prior art.
Moreover, when the laser beam passes a focusing lens for machining, in the case of machining the center portion of the processing area by the scanning mirror, the laser beam is irradiated vertically to the object of machining. In the case of machining of peripheral portion, however, the laser beam is not irradiated vertically to the object of machining, and the laser beam reflected from the workpiece may be dislocated from the intermediate optical system parts, or may be irradiated to the optical parts holding portion, and the laser beam reflected from the workpiece may be diffused on the way, and part of the reflected beam may not reach the reflected beam detector. As a result, detection of reflected beam is imperfect, thereby lowering the precision of judgement of machining state of drilled holes.
Or, if the table on which the workpiece is mounted is inclined, similarly, part of the laser beam reflected from the workpiece may not return to the detector of laser beam. As a result, the reflected beam is not detected accurately, and the precision of judgement of machining sate of drilled holes is lowered. The prior art involved also such problems.
In the beam of the above background, it is a first object of the invention to set the condition and maximum number of outputs in every one pulse output of laser capable of machining the workpiece securely. That is, if reaching the specified level by comparison with the reference value before reaching the preset number of outputs, it is controlled to stop the laser output unit. As a result, laser machining is increased in speed. Setting of the maximum number of outputs prevents excessive machining. Therefore, high quality hole drilling is realized at high yield of machining.
It is a second object to detect the laser beam reflected from the workpiece by a detector, and correct the intensity signal of the detected laser beam. That is, the laser beam reflected from the workpiece is detected by a detector, the intensity signal of the detected laser beam is corrected, and the intensity of the laser beam reflected from the workpiece is calculated accurately. As a result, the machining state of drilled holes is detected accurately, and holes are drilled at high quality.
It is hence an object of the invention to present a laser machining apparatus and its control method capable of increasing the laser machining speed, enhancing the machining yield, and realizing high quality hole drilling.
A first aspect of the invention to achieve the objects is described. A first step is for executing laser machining after setting the number of laser outputs as the laser output condition for drilling holes in the workpiece by plural times of laser pulse outputs. A second step is for detecting the machining state of the workpiece in the process of execution of laser machining, and judging if reaching the desired machining state or not by laser machining. A next step is for finishing the laser machining when judging the workpiece has reached the desired machining state, if not reaching the set number of laser outputs, and otherwise continuing the laser machining up to the set number of laser outputs. In this way, laser machining is done in three steps.
A second aspect of the invention is described. A first step is for executing laser machining after setting the number of laser outputs as the laser output condition for drilling holes in the workpiece by plural times of laser pulse outputs. A second step is for detecting the machining state of the workpiece in the process of execution of laser machining, and judging if reaching the desired machining state or not by laser machining. A third step is for finishing the laser machining when judging the workpiece has reached the desired machining state, if not reaching the set number of laser outputs, and otherwise continuing the laser machining up to the set number of laser outputs. A next step is for processing error when judging the workpiece has not reached the desired machining state in the case of executing laser machining up to the set number of laser outputs. In this way, laser machining is done in four steps.
A third aspect of the invention is described. A first step is for executing laser machining after setting the number of laser outputs as the laser output condition for drilling holes in the workpiece by plural times of laser pulse outputs. A second step is for detecting the machining state of the workpiece in the process of execution of laser machining, and judging if reaching the desired machining state or not by laser machining. A third step is for finishing the laser machining when judging the workpiece has reached a first desired machining state, if not reaching the set number of laser outputs, and otherwise continuing the laser machining up to the set number of laser outputs. A fourth step is for detecting the machining state of the workpiece when laser machining is executed up to the set number of laser outputs, and judging if reaching a second desired machining state or not by laser machining. In this way, laser machining is done in four steps.
A fourth aspect of the invention is described. A first step is for executing laser machining after setting the number of laser outputs as the laser output condition for drilling holes in the workpiece by plural times of laser pulse outputs. A second step is for detecting the machining state of the workpiece in the process of execution of laser machining, and judging if reaching the desired machining state or not by laser machining. A third step is for finishing the laser machining when judging the workpiece has reached a first desired machining state, if not reaching the set number of laser outputs, and otherwise continuing the laser machining up to the set number of laser outputs. A fourth step is for detecting the machining state of the workpiece when laser machining is executed up to the set number of laser outputs, and judging if reaching a second desired machining state or not by laser machining. A fifth step is for processing error if not reaching the second desired machining state. In this way, laser machining is done in five steps.
A fifth aspect of the invention is described. A first step is for setting at least a first number of laser outputs as the laser output condition for drilling holes in the workpiece by plural times of laser pulse outputs. A second step is for setting a second number of laser outputs smaller than the first number of laser outputs. A third step is for executing laser machining up to the second number of laser outputs. A fourth step is for detecting the machining state of the workpiece in the process of execution of laser machining from the second number of laser outputs to the first number of laser outputs, and judging if reaching the desired machining state or not by laser machining. A fifth step is for finishing the laser machining when judging the workpiece has reached the desired machining state, if not reaching the first number of laser outputs, and otherwise continuing the laser machining up to the first number of laser outputs. In this way, laser machining is done in five steps.
A sixth aspect of the invention is described. A first step is for setting at least a first number of laser outputs as the laser output condition for drilling, holes in the workpiece by plural times of laser pulse outputs. A second step is for setting a second number of laser outputs smaller than the first number of laser outputs. A third step is for executing laser machining up to the second number of laser outputs. A fourth step is for detecting the machining state of the workpiece in the process of execution of laser machining from the second number of laser outputs to the first number of laser outputs, and judging if reaching the desired machining state or not by laser machining. A fifth step is for finishing the laser machining when judging the workpiece has reached the desired machining state, if not reaching the first number of laser outputs, and otherwise continuing the laser machining up to the first number of laser outputs. A sixth step is for processing error when judging the workpiece has not reached the desired machining state in the case of executing laser machining up to the first number of laser outputs. In this way, laser machining is done in six steps.
A seventh aspect of the invention is described. A first step is for setting at least a first number of laser outputs as the laser output condition for drilling holes in the workpiece by plural times of laser pulse outputs. A second step is for setting a second number of laser outputs smaller than the first number of laser outputs. A third step is for executing laser machining up to the second number of laser outputs. A fourth step is for detecting the machining state of the workpiece in the process of execution of laser machining from the second number of laser outputs to the first number of laser outputs, and judging if reaching the desired machining state or not by laser machining. A fifth step is for finishing the laser machining when judging the workpiece has reached a first desired machining state, if not reaching the first number of laser outputs, and otherwise continuing the laser machining up to the first number of laser outputs. A sixth step is for detecting the machining state of the workpiece in the case of executing laser machining up to the first number of laser outputs, and judging if reaching a second desired machining state or not by laser machining. In this way, laser machining is done in six steps.
An eighth aspect of the invention is described. A first step is for setting at least a first number of laser outputs as the laser output condition for drilling holes in the workpiece by plural times of laser pulse outputs. A second step is for setting a second number of laser outputs smaller than the first number of laser outputs. A third step is for executing laser machining up to the second number of laser outputs. A fourth step is for detecting the machining state of the workpiece in the process of execution of laser machining from the second number of laser outputs to the first number of laser outputs, and judging if reaching a first desired machining state or not by laser machining. A fifth step is for finishing the laser machining when judging the workpiece has reached the first desired machining state, if not reaching the first number of laser outputs, and otherwise continuing the laser machining up to the first number of laser outputs. A sixth step is for detecting the machining state of the workpiece in the case of executing laser machining up to the first number of laser outputs, and judging if reaching a second desired machining state or not by laser machining. A seventh step is for processing error if not reaching the second desired machining state. In this way, laser machining is done in seven steps.
A ninth aspect of the invention relates to the laser machining method of any one of the fifth to eighth aspects of the invention, in which the first number of laser outputs is set at a numerical value capable of machining securely, in the relation between the workpiece and the laser output, and the second number of laser outputs is set at a value capable of machining sufficiently.
A tenth aspect of the invention relates to the laser machining method of any one of the third, fourth, seventh and eighth aspects of the invention, in which the first desired machining state is closer to the desired machining state as compared with the second desired machining state.
An eleventh aspect of the invention relates to the laser machining method of any one of the first to tenth aspects of the invention, in which the ratio of the laser output intensity and the reflected beam intensity from the workpiece is used at the step of detecting the machining state of the workpiece and judging if reaching the desired machining state or not by laser machining.
A twelfth aspect of the invention is a control method of a laser machining apparatus of any one of the first to eleventh aspects of the invention, relating to a control method of laser machining apparatus for machining by irradiating a laser beam from a laser output unit to the workpiece, in which the beam intensity of the reflected beam from the workpiece is detected by a reflected beam detector, the reflected beam intensity right after reflection from the workpiece is calculated according to the data of the reflected beam distribution table storing the rate of change of the reflected beam from the workpiece until reaching the reflected beam detector in every machining position of the workpiece, and the laser output unit is controlled according to the comparison between the calculated reflected beam intensity and the reference value.
A thirteenth aspect of the invention is a control method of a laser machining apparatus of any one of the first to twelfth aspects of the invention, relating to a control method of laser machining apparatus for machining by irradiating a laser beam from a laser output unit to the workpiece, in which the intensity of the laser beam is detected by an incident beam detector as an incident beam intensity, the beam intensity of the reflected beam from the workpiece is detected by a reflected beam detector, the reflected beam intensity right after reflection from the workpiece is calculated from the data of the reflected beam distribution table storing the rate of change of the reflected beam from the workpiece until reaching the reflected beam detector in every machining position of the workpiece and the output of the reflected beam detector, and the laser output unit is controlled according to the comparison between the relative reflected beam intensity operated from the incident beam intensity and the calculated reflected beam intensity and its reference value.
A fourteenth aspect of the invention is a control method of a laser machining apparatus of any one of the first to thirteenth aspects of the invention, relating to the laser machining method of the thirteenth aspect of the invention, in which the formula for determining the relative reflected beam intensity from the incident beam intensity and reflected beam intensity is expressed in formula 1.
Relative reflected beam intensity of n-th pulse=(cnxe2x88x92c1)/(cmaxxe2x88x92c1)xe2x80x83xe2x80x83(Formula 1)
where k: an arbitrary constant
an: n-th incident laser beam intensity
bn: n-th reflected laser beam intensity
amax: maximum value of information about incident laser beam intensity
bmax: maximum value of information about reflected laser beam intensity
cn: kxc3x97(bn/an)
cmax: kxc3x97(bmax/amax)
A fifteenth aspect of the invention is a control method of a laser machining apparatus of any one of the twelfth to fourteenth aspects of the invention, relating to a control method of laser machining apparatus for machining by irradiating a laser beam from a laser output unit to the workpiece, in which the intensity of the laser beam is detected by an incident beam detector as an incident beam intensity, the beam intensity of the reflected beam from a fixed mirror placed at a position for mounting the workpiece is detected by a reflected beam detector, the rate of the reflected beam intensity of the reflected beam right after reflection from the fixed mirror reaching the reflected beam detector is calculated from the reflected beam intensity detected by the reflected beam detector when irradiating the laser beam to the machining coordinates positions of the workpiece and the incident beam intensity detected by the incident beam detector, and the laser output unit is controlled according to the comparison between the data of the reflected beam distribution table storing the result of the calculation and the reference value.
A sixteenth aspect of the invention is a control method of a laser machining apparatus relating to the laser machining method of any one of the twelfth to fifteenth aspects of the invention, in which the data of the rate of the reflected beam reaching the reflected beam detector is stored in the reflected beam distribution table at machining positions provided at equal intervals.
A seventeenth aspect of the invention is a control method of a laser machining apparatus relating to the laser machining method of any one of the twelfth to fifteenth aspects of the invention, in which the data of the rate of the reflected beam reaching the reflected beam detector is stored in the reflected beam distribution table in rough divisions in the central portion of the machining region, and in fine divisions in the peripheral portion.
An eighteenth aspect of the invention is a control method of a laser machining apparatus, relating to a control method of laser machining apparatus for machining by irradiating a laser beam from a laser output unit to the workpiece, in which the beam intensity of the reflected beam from the workpiece is detected by a reflected beam detector, the reflected beam intensity right after reflection from the workpiece is calculated according to the data of the reflected beam distribution table storing the rate of change of the reflected beam from the workpiece until reaching the reflected beam detector in every machining position of the workpiece, and the laser output unit is controlled according to the comparison between the calculated reflected beam intensity and the reference value.
A nineteenth aspect of the invention is a control method of a laser machining apparatus, relating to a control method of laser machining apparatus for machining by irradiating a laser beam from a laser output unit to the workpiece, in which the intensity of the laser beam is detected by an incident beam detector as an incident beam intensity, the beam intensity of the reflected beam from the workpiece is detected by a reflected beam detector, the reflected beam intensity right after reflection from the workpiece is calculated from the data of the reflected beam distribution table storing the rate of change of the reflected beam from the workpiece until reaching the reflected beam detector in every machining position of the workpiece and the output of the reflected beam detector, and the laser output unit is controlled according to the comparison between the relative reflected beam intensity operated from the incident beam intensity and the calculated reflected beam intensity and its reference value.
A twentieth aspect of the invention is a control method of a laser machining apparatus, relating to the laser machining method of the nineteenth aspect of the invention, in which the formula for determining the relative reflected beam intensity from the incident beam intensity and reflected beam intensity is expressed in formula 1.
A twenty-first aspect of the invention is a control method of a laser machining apparatus, relating to a control method of laser machining apparatus for machining by irradiating a laser beam from a laser output unit to the workpiece, in which the intensity of the laser beam is detected by an incident beam detector as an incident beam intensity, the beam intensity of the reflected beam from a fixed mirror placed at a position for mounting the workpiece is detected by a reflected beam detector, the rate of the reflected beam intensity of the reflected beam right after reflection from the fixed mirror reaching the reflected beam detector is calculated from the reflected beam intensity detected by the reflected beam detector when irradiating the laser beam to the machining coordinates positions of the workpiece and the incident beam intensity detected by the incident beam detector, and the laser output unit is controlled according to the comparison between the data of the reflected beam distribution table storing the result of the calculation and the reference value.
A twenty-second aspect of the invention is a control method of a laser machining apparatus relating to the laser machining method of any one of the eighteenth to twenty-first aspects of the invention, in which the data of the rate of the reflected beam reaching the reflected beam detector is stored in the reflected beam distribution table at machining positions provided at equal intervals.
A twenty-third aspect of the invention is a control method of a laser machining apparatus relating to the laser machining method of any one of the eighteenth to twenty-first aspects of the invention, in which the data of the rate of the reflected beam reaching the reflected beam detector is stored in the reflected beam distribution table in rough divisions in the central portion of the machining region, and in fine divisions in the peripheral portion.
A twenty-fourth aspect of the invention presents a laser machining apparatus comprising:
a laser output unit for drilling holes in the workpiece by plural times of laser pulse outputs,
a setting unit for setting the number of laser outputs as laser output condition,
a detector for detecting the machining state of the workpiece,
a judging unit for judging if reaching a desired machining state by a signal from the detector, and
a controller for controlling the laser output unit by receiving a signal from the judging unit,
in which the controller finishes laser machining when judging the workpiece has reached the desired machining state, if not reaching the set number of laser outputs, and otherwise continues the execution of laser machining up to the set number of laser outputs.
A twenty-fifth aspect of the invention presents a laser machining apparatus comprising:
a laser output unit for drilling holes in the workpiece by plural times of laser pulse outputs,
a setting unit for setting the number of laser outputs as laser output condition,
a detector for detecting the machining state of the workpiece,
a judging unit for judging if reaching a desired machining state by a signal from the detector, and
a controller for controlling the laser output unit by receiving a signal from the judging unit,
in which the controller finishes laser machining when judging the workpiece has reached the desired machining state, if not reaching the set number of laser outputs, and otherwise continues the execution of laser machining up to the set number of laser outputs, and
an error is processed when judging the workpiece has not reached the desired machining state in the case of executing laser machining up to the set number of laser outputs.
A twenty-sixth aspect of the invention presents a laser machining apparatus comprising:
a laser output unit for drilling holes in the workpiece by plural times of laser pulse outputs,
a setting unit for setting the number of laser outputs as laser output condition,
a detector for detecting the machining state of the workpiece,
a judging unit for judging if reaching a desired machining state by a signal from the detector, and
a controller for controlling the laser output unit by receiving a signal from the judging unit,
in which the controller finishes laser machining when judging the workpiece has reached a first desired machining state, if not reaching the set number of laser outputs, and otherwise continues the execution of laser machining up to the set number of laser outputs, and
the judging unit judges if reaching a second desired machining state in the case of executing laser machining up to the set number of laser outputs.
A twenty-seventh aspect of the invention presents a laser machining apparatus comprising:
a laser output unit for drilling holes in the workpiece by plural times of laser pulse outputs,
a setting unit for setting the number of laser outputs as laser output condition,
a detector for detecting the machining state of the workpiece,
a judging unit for judging if reaching a desired machining state by a signal from the detector, and
a controller for controlling the laser output unit by receiving a signal from the judging unit,
in which the controller finishes laser machining when judging the workpiece has reached a first desired machining state, if not reaching the set number of laser outputs, and otherwise continues the execution of laser machining up to the set number of laser outputs,
the judging unit detects the machining state of the workpiece and judges if reaching a second desired machining state by laser machining in the case of executing laser machining up to the set number of laser outputs, and
an error is processed when not reaching the second desired machining state.
A twenty-eighth aspect of the invention presents a laser machining apparatus comprising:
a laser output unit for drilling holes in the workpiece by plural times of laser pulse outputs,
a setting unit for setting a first number of laser outputs and a second number of laser outputs smaller than the first number of laser outputs as laser output condition,
a detector for detecting the machining state of the workpiece,
a judging unit for judging if reaching a desired machining state by a signal from the detector during execution of laser machining from the second number of laser outputs to the first number of laser outputs, and
a controller for controlling the laser output unit by receiving a signal from the judging unit,
in which the controller finishes laser machining when judging the workpiece has reached the desired machining state, if not reaching the first number of laser outputs during laser machining after the second number of laser outputs, and otherwise continues the execution of laser machining up to the first number of laser outputs.
A twenty-ninth aspect of the invention presents a laser machining apparatus comprising:
a laser output unit for drilling holes in the workpiece by plural times of laser pulse outputs,
a setting unit for setting a first number of laser outputs and a second number of laser outputs smaller than the first number of laser outputs as laser output condition,
a detector for detecting the machining state of the workpiece,
a judging unit for judging if reaching a desired machining state by a signal from the detector during execution of laser machining from the second number of laser outputs to the first number of laser outputs, and
a controller for controlling the laser output unit by receiving a signal from the judging unit,
in which the controller finishes laser machining when judging the workpiece has reached the desired machining state, if not reaching the first number of laser outputs during laser machining after the second number of laser outputs, and otherwise continues the execution of laser machining up to the first number of laser outputs, and
an error is processed when judging the workpiece has not reached the desired machining state in the case of execution of laser machining up to the first number of laser outputs.
A thirtieth aspect of the invention presents a laser machining apparatus comprising:
a laser output unit for drilling holes in the workpiece by plural times of laser pulse outputs,
a setting unit for setting a first number of laser outputs and a second number of laser outputs smaller than the first number of laser outputs as laser output condition,
a detector for detecting the machining state of the workpiece,
a judging unit for judging if reaching a desired machining state by a signal from the detector during execution of laser machining from the second number of laser outputs to the first number of laser outputs, and
a controller for controlling the laser output unit by receiving a signal from the judging unit,
in which the controller finishes laser machining when judging the workpiece has reached a first desired machining state, if not reaching the first number of laser outputs during laser machining after the second number of laser outputs, and otherwise continues the execution of laser machining up to the first number of laser outputs, and
the judging unit judges if reaching a second desired machining state in the case of execution of laser machining up to the first number of laser outputs.
A thirty-first aspect of the invention presents a laser machining apparatus comprising:
a laser output unit for drilling holes in the workpiece by plural times of laser pulse outputs,
a setting unit for setting a first number of laser outputs and a second number of laser outputs smaller than the first number of laser outputs as laser output condition,
a detector for detecting the machining state of the workpiece,
a judging unit for judging if reaching a desired machining state by a signal from the detector during execution of laser machining from the second number of laser outputs to the first number of laser outputs, and
a controller for controlling the laser output unit by receiving a signal from the judging unit,
in which the controller finishes laser machining when judging the workpiece has reached a first desired machining state, if not reaching the first number of laser outputs during laser machining after the second number of laser outputs, and otherwise continues the execution of laser machining up to the first number of laser outputs,
the judging unit detects the machining state of the workpiece and judges if reaching a second desired machining state by laser machining in the case of execution of laser machining up to the first number of laser outputs, and
an error is processed if not reaching the second desired machining state.
A thirty-second aspect of the invention presents a laser machining apparatus of any one of the twenty-eighth to thirty-first aspects of the invention, in which the first number of laser outputs is set at a numerical value capable of machining securely, in the relation between the workpiece and the laser output, and the second number of laser outputs is set at a value capable of machining sufficiently.
A thirty-third aspect of the invention presents a laser machining apparatus of any one of the twenty-sixth, twenty-seventh, thirtieth, and thirty-first aspects of the invention, in which the first desired machining state is closer to the desired machining state as compared with the second desired machining state.
A thirty-fourth aspect of the invention presents a laser machining apparatus of any one of the twenty-fourth to thirty-third aspects of the invention, in which the ratio of the laser output intensity and the reflected beam intensity from the workpiece is used at the step of detecting the machining state of the workpiece and judging if reaching the desired machining state or not by laser machining.
A thirty-fifth aspect of the invention presents a laser machining apparatus of the twenty-fourth to thirty-fourth aspects of the invention comprising a laser output unit for irradiating a laser beam, an optical system structure for guiding the laser beam into the workpiece, and a control unit for controlling the laser output unit, and further including a reflected beam detector for detecting the beam intensity of the reflected beam from the workpiece, a reflected beam distribution table storing the rate of change of the reflected beam from the workpiece until reaching the reflected beam detector in every machining position of the workpiece, and a reflected beam intensity calculator for calculating the reflected beam intensity right after reflection from the workpiece from the reflected beam detector and the reflected beam distribution table, in which the laser output unit is controlled by the control unit according to the comparison between the reflected beam intensity calculated by the reflected beam intensity calculator and its reference value.
A thirty-sixth aspect of the invention presents a laser machining apparatus of the twenty-fourth to thirty-fifth aspects of the invention comprising a laser output unit for irradiating a laser beam, an optical system structure for guiding the laser beam into the workpiece, and a control unit for controlling the laser output unit, and further including an incident beam detector for detecting the intensity of the laser beam, a reflected beam detector for detecting the beam intensity of the reflected beam from the workpiece, a reflected beam distribution table storing the rate of change of the reflected beam from the workpiece until reaching the reflected beam detector in every machining position of the workpiece, and a reflected beam intensity calculator for calculating the reflected beam intensity right after reflection from the workpiece from the reflected beam detector and the reflected beam distribution table, in which the laser output unit is controlled by the control unit according to the comparison between the relative reflected beam intensity operated from the incident beam intensity detected by the incident beam detector and the reflected beam intensity calculated by the reflected beam intensity calculator and its reference value.
A thirty-seventh aspect of the invention presents a laser machining apparatus relating to the laser machining apparatus of the thirty-sixth aspect of the invention, in which the formula for determining the relative reflected beam intensity from the incident beam intensity and reflected beam intensity is expressed in formula 1.
A thirty-eighth aspect of the invention presents a laser machining apparatus of the thirty-fifth to thirty-seventh aspects of the invention comprising a laser output unit for irradiating a laser beam, an optical system structure for guiding the laser beam into the workpiece, and a control unit for controlling the laser output unit, and further including an incident beam detector for detecting the intensity of the laser beam, a fixed mirror placed at a position for mounting the workpiece, a reflected beam detector for detecting the beam intensity of the reflected beam from the fixed mirror, a reflected beam distribution calculator for calculating the rate of the reflected beam intensity of the reflected beam right after reflection from the fixed mirror reaching the reflected beam detector from the reflected beam intensity detected by the reflected beam detector when irradiating the laser beam to the machining coordinates positions of the workpiece and the incident beam intensity detected by the incident beam detector, and a reflected beam distribution table storing the result of calculation of the reflected beam distribution calculator.
A thirty-ninth aspect of the invention is a laser machining apparatus of any one of the thirty-fifth to thirty-eighth aspects of the invention, in which the data of the rate of the reflected beam reaching the reflected beam detector is stored in the reflected beam distribution table at machining positions provided at equal intervals.
A fortieth aspect of the invention is a laser machining apparatus of any one of the thirty-fifth to thirty-eighth aspects of the invention, in which the data of the rate of the reflected beam reaching the reflected beam detector is stored in the reflected beam distribution table in rough divisions in the central portion of the machining region, and in fine divisions in the peripheral portion.
A forty-first aspect of the invention presents a laser machining apparatus comprising a laser output unit for irradiating a laser beam, an optical system structure for guiding the laser beam into the workpiece, and a control unit for controlling the laser output unit, and further including a reflected beam detector for detecting the beam intensity of the reflected beam from the workpiece, a reflected beam distribution table storing the rate of change of the reflected beam from the workpiece until reaching the reflected beam detector in every machining position of the workpiece, and a reflected beam intensity calculator for calculating the reflected beam intensity right after reflection from the workpiece from the reflected beam detector and the reflected beam distribution table, in which the laser output unit is controlled by the control unit according to the comparison between the reflected beam intensity calculated by the reflected beam intensity calculator and its reference value.
A forty-second aspect of the invention presents a laser machining apparatus comprising a laser output unit for irradiating a laser beam, an optical system structure for guiding the laser beam into the workpiece, and a control unit for controlling the laser output unit, and further including an incident beam detector for detecting the intensity of the laser beam, a reflected beam detector for detecting the beam intensity of the reflected beam from the workpiece, a reflected beam distribution table storing the rate of change of the reflected beam from the workpiece until reaching the reflected beam detector in every machining position of the workpiece, and a reflected beam intensity calculator for calculating the reflected beam intensity right after reflection from the workpiece from the reflected beam detector and the reflected beam distribution table, in which the laser output unit is controlled by the control unit according to the comparison between the relative reflected beam intensity operated from the incident beam intensity detected by the incident beam detector and the reflected beam intensity calculated by the reflected beam intensity calculator and its reference value.
A forty-third aspect of the invention relates to the laser machining apparatus of the forty-second aspect of the invention, in which the formula for determining the relative reflected beam intensity from the incident beam intensity and reflected beam intensity is expressed in formula 1.
A forty-fourth aspect of the invention presents a laser machining apparatus comprising a laser output unit for irradiating a laser beam, an optical system structure for guiding the laser beam into the workpiece, and a control unit for controlling the laser output unit, and further including an incident beam detector for detecting the intensity of the laser beam, a fixed mirror placed at a position for mounting the workpiece, a reflected beam detector for detecting the beam intensity of the reflected beam from the fixed mirror, a reflected beam distribution calculator for calculating the rate of the reflected beam intensity of the reflected beam right after reflection from the fixed mirror reaching the reflected beam detector from the reflected beam intensity detected by the reflected beam detector when irradiating the laser beam to the machining coordinates positions of the workpiece and the incident beam intensity detected by the incident beam detector, and a reflected beam distribution table storing the result of calculation of the reflected beam distribution calculator.
A forty-fifth aspect of the invention is a laser machining apparatus of any one of the forty-first to forty-fourth aspects of the invention, in which the data of the rate of the reflected beam reaching the reflected beam detector is stored in the reflected beam distribution table at machining positions provided at equal intervals.
A forty-sixth aspect of the invention is a laser machining apparatus of any one of the forty-first to forty-fourth aspects of the invention, in which the data of the rate of the reflected beam reaching the reflected beam detector is stored in the reflected beam distribution table in rough divisions in the central portion of the machining region, and in fine divisions in the peripheral portion.